1. Field
The subject matter disclosed herein relates to electronic devices, and more particularly to methods and apparatuses for use in providing positioning assistance data with local mapping data to mobile stations.
2. Information
The Global Positioning System (GPS) and other like satellite positioning systems have enabled navigation services for mobile handsets in outdoor environments. Since satellite signals may not be always be reliably received and/or acquired in an indoor environment, different techniques may be employed to enable position estimation and related navigation services. For example, mobile stations can typically obtain a position fix by measuring ranges to three or more terrestrial radio transmitters which are positioned at known locations. Such ranges may be measured, for example, by obtaining a MAC ID address from signals received from such access points and measuring one or more characteristics of signals received from such access points such as, for example, signal strength, round trip delay, just to name a few examples.
By way of additional example, a mobile station, such as, a mobile phone, smart phone, etc., may perform signal-based position estimation to identify its location within a structure by taking measurements, for example of a signal strength (e.g., an RSSI) and/or propagation time (e.g., a round-trip time (RTT)) for signals exchanged with various radio transmitters (e.g., access points, beacons, etc.). A mobile station may use these or other like measurements to obtain a probability distribution over a region of space (e.g., defined using two or coordinates (x, y), etc.). Such a probability distribution or other like information may, for example, be used in a particle filter, Kalman filter, and/or other positioning mechanism using known techniques.
In some implementations, an indoor navigation system may provide a digital electronic map to mobile stations, e.g., as a user enters a particular indoor area. Such a map may show indoor features such as doors, hallways, entry ways, walls, etc., points of interest such as bathrooms, pay phones, room names, stores, etc. Such a digital electronic map may be stored at a server to be accessible by a mobile station through selection of an Internet based URL, for example. Thus, to obtain such a map, a mobile station may need to leave a serving network or other cellular network and/or otherwise access a local area network and/or the Internet. By obtaining and displaying such a map, a mobile station may overlay a current location of the mobile station (and user) over the displayed map to provide the user with additional context. Using map information indicating routing constraints, a mobile station may also apply location estimates to estimating a trajectory of the mobile station in an indoor area subject to the routing constraints.